Process for the treatment of tobacco



United States Patent 3,256,888 PROCESS FOR THE TREATMENT OF TOBACCO Roger T... de la Burd, Richmond, Va. N0 Drawing. Filed Nov. 30, 1962, Ser. No. 241,123 4 Claims. (Cl. 131141) This invention relates to a process for the treatment of tobacco. More particularly, the invention relates to a process for improving the smoking characteristics of tobacco.

It has long been a problem in the art that freshly harvested tobacco generally requires several years, involving a number of differenttreatments, before it is ready to be used in smoking products. For example, the harvested tobacco is generally'dried for several months in order to cure it and the cured tobacco thereafter undergoes a number of sweating, redrying, resweating and aging operations which extend over a period of two to three years.

Numerous attempts have been made to shorten the period of time necessary to convert freshly harvested tobacco to a smoking product which has desirable flavor and smoking qualities. For example, bacteria have been added to tobacco and catalysts have been incorporated in tobacco in order to accelerate the fermentation process. However, none of these attempts has been found to be completely satisfactory.

It is an object of the present invention to provide an 4 improved process for treating tobacco to improve the smoking characteristics thereof.

It is another object of the present invention to provide a process for upgrading tobacco to a satisfactory level of flavor and smoking qualities in a relatively short period of time.

It is also an object of the present invention to eliminate the disadvantageous changes which occur in the moisture retention properties of tobacco which has been treated by the conventional aging processes.

Additional objects of the present invention will be apparent from the following description.

I have discovered that the smoking characteristics of tobacco are greatly improved by the addition of a proteolytic enzyme to the tobacco.

In accordance with the present invention, a proteolytic enzyme is added to tobacco in an amount suflicient to provide a tobacco composition containing from about 1.4 to about 2.8 grams, and preferably from about 2.0 to about 2.5 grams of proteolytic' enzyme per pound of tobacco.

The enzyme can be applied in any suitable manner. However, it is generally applied to the tobacco in the form of a liquid solution suspension or emulsion by spraying, dipping, brushing or other means.

The enzyme is preferably added to the tobacco as an aqueous solution having a concentration of about 3 to 7% by weight, with sufficient solution being added to bring the tobacco to a moisture content of from about 15 to about 45 and is most preferably added to the tobacco as a 4.0 to 5.5 solution, with sufficient solution to bring the tobacco to a moisture content of from about 15 to about 30% by weight.

The preferred method of adding the enzyme is to spray a solution of it on tobacco leaves, since by this method the moisture content of the sprayed leaves can readily be v controlled. The pH of the enzyme solution can be adjusted to a value between about 4.2 and 8.6 by the addi tion of suitable agents, such as sodium hydroxide, ammonium' hydroxide, acetic acid, hydrochloric acid, etc. and is preferably adjusted to a value of from about 5.5 to about 7.5, in order to best facilitate the action of the enzyme.

The moisture content of the treated leaves is important and should be from about 15% to about 45% after the addition of enzyme. At least 15% moisture is necessary in order to produce a product having sufiicient mildness. The upper limit'of 45% is necessary, since raising the moisture content of the leaves above this value irreversibly decreases some of the improved smoking characteristics which would otherwise be obtained by the present enzyme treatment of the leaves.

The addition of the enzyme to the tobacco can be conducted at temperatures of from about 60 to about 120 F.,

but is preferably conducted at room temperature.

The proteolytic enzymes of this invention include ficin, pepsin, trypsin, chymotrypsin, erepsin, fungal protease, protease, papain and the like and may be employed either alone or in combination with one another. These enzymes can be obtained from a variety of sources. For example, ficin is a powerful proteolytic enzyme preparation obtained from the latex of a fig tree; fungal protease is a proteolytic enzyme derived from Aspergillus oryzae; HT proteolytic (Miles Chemical Co.) is a proteolytic enzyme preparation derived from a bacterial source; pepsin is a proteolytic enzyme obtained from hog stomach mucosa; protease is a proteolytic enzyme preparation derived from sheep pancreas; papain is a protease derived from the latex of the fruit of Carz'cqz papaya and trypsin and chymotrypsin and lyophilized proteolytic enzymes isolated from beef pancreas.

The enzyme should be evenly distributed throughout the tobacco leaves. It can then be placed in suitable containers, such as polyethylene bags, which will prevent evaporation of moisture in the mixture.

The resulting enzyme-tobacco mixtures can then be placed in an atmosphere, for example a humidity cabinet, maintained at about 60 to about 140 F. and about 45 to about 85% relative humidity. for a period of from about 1 to about 200 hours.

The tobacco parts can then be removed from the above atmosphere and can be placed in an environment maintained at a temperature of from about 60 to about 80 F. and about 60 to about relative humidity, in order to permit the moisture content of the leaves to reach a value of from about 12% to about 14%.

Tobaccos which can be treated in accordance with the present invention can be of any quality or. origin. For example, the tobacco. can be low grade or high grade domestic tobaccos, for example burley, Maryland, bright or Virginia tobaccos or mixtures of these. The tobacco can also be, for example, an imported aromatic or oriental tobacco or mixtures of these, including mixtures with domestic tobaccos.

The tobacco is preferably treated in full leaf form but can also be cut, sliced or otherwise comminuted before The following examples are illustrative:

Example] Ten pounds of full leaves of a low-grade bright tobacco (RDZ) were employed in this example. Two and a half pound batches were separately sprayed with 0.2, 1.0, 3.0, and 5.0% aqueous solutions, respectively of Protease NBC, a pancreatic extract (Armour Co.), inamounts sufiicient to bring the moisture content of the tobacco from 10% to 18%.

Each batch of leaves so treated was mixed thoroughly and packed loosely in polyethylene bags. The bags were closed to prevent evaporation of the moisture and were then placed in humidity cabinets maintained at a temperature of 100 F. and at 70% relative humidity (R.H.) for 60 hours.

Following this treatment, the leaves were removed from the polyethylene bags and placed loosely on wire mats in a room maintained at a temperature of 75 C. and at a relative humidity of 60%, until the moisture in theleaf had a value of about 12% by weight, which required about 24 to 30 hours.

In each case, visual examination of the leaves showed no change in the appearance of the tobacco. No darken-' ing of the tobacco was observed.

Cigarettes were then prepared from each batch of leaves and from unagcd and force-aged" tobacco of the same low-grade stock.

Data on the subjective evaluation of the smoke from the cigarettes by a smoking panel of nine members showed that the enzyme treatment developed the desirable flavor and mildness characteristic of the tobacco. No increase in the sweetness of the smoke was observed. The flavor, aroma, and rnildness characteristics were found to be greatly improved in cigarettes prepared from tobacco treated with proteinase at a concentration range between 3 and 6% over a control cigarette made of naturally aged tobacco. The results of the evaluations are given in Table I below.

TABLE I.TEST PANEL EVALUATIONS OF LOW GRADE BRIGHT TOBACCO CONTAINING PROTEINASE Average Rating From 9 Panelists 1 A scale of 5 to +5 was employed, 5 being the poorest rating, being the characteristics of the control, and being the best rating.

Example 2 Eighteen pounds of the same type of low-grade (RDZ) bright tobacco which was used in Example 1 was treated in two-pound batches with 0.2, 1.0, and 5.0% aqueous solutions of erepsin, respectively. The solution was applied in one case (0.2, 1.0, 5.0% concentration) by dipping the leaves, in another case (0.2, 1.0, 5.0% concentration) by spraying them up to saturation (which was 45%) and in another case (0.2, 1.0, 5.0% concentration) by spraying them with quantities suflicient to bring the moisture content to a 20% level. The leaves were then placed loosely in a polyethylene bag and conditioned for 60 hours in humidity cabinets. The samples were placed on trays and conditioned at 100 F. and 75% RH. for 24 hours until the percentage of the moisture was about 12%. It was observed that the treatment had caused the tobacco to darken.

Cigarettes were made from the erepsin-treated tobacco and from a control. These cigarettes were evaluated by *Force-agedtobacco which has been submitted to an accelerated aging process in accordance with the process set forth by F. Darkes in Industrial and Engineering Chemistry, 44, p. 284 (1952).

being the characteristics of the control, and +5 being the best rating.

d a smoking panel. The smoke from the treated cigarettes was milder than that from the control cigarette. The results of these evaluations are given in Table II, below:

TABLE II.-TEST PANEL EVALUATIONS OF LOW GRADE BRIGHT TOBACCO CONTAINING EREPSIN 1 A scale of 5 to +5 was employed, 5 being the poorest rating,

0 being the characteristics of the control, and +5 being the best rating.

Six pounds of the same type of low-grade (RDZ) bright tobacco which was used in Example 1 was treated in three two-pound batches with 1.0, 4.0 and 5.0% aqueous solutions of pepsin, respectively. The solutions were applied by spraying to 20% moisture content, moisture equilibrium was maintained in the tobacco system at a constant 67% relative humidity. The tobacco was then kept in closed pans under partial pressure for 48 hours at a temperature of 120 F., taken off and maintained for an additional period of 24 hours at gradually decreasing relative humidity until the moisture content of the tobacco was brought to the level of 15%. The samples were then placed on trays and conditioned at F. and 82% relative humidity for an additional period of 48 hours.

Cigarettes were made from the pepsin-treated tobacco and from a control. These cigarettes were evaluated by a smoking panel. The smoke from the treated cigarettes was milder than that from the control cigarette. The results of these evaluations are given in Table III below:

TABLE III.-TEST PANEL EVALUATIONS OF LOW GRADE BRIGHT TOBACCO CONTAINING PEPSIN Average rating from 9 Panelists Percent Concentration Harshness Aroma Desirability *A scale of 5 to +5 was employed, -5 being the poorest rating, 0

Example 4 Two pounds of the same type of low-grade (RDZ) bright tobacco which was used in Example 1 was treated with 0.5 and 5.0% aqueous solutions of a mixture of plant papain and plant ficin. The solution was applied by spraying to a 25% moisture content in the tobacco. The tobacco was then exposed for 60 hours in sealed jars to a temperature of F. Tobacco was then taken out and brought to 12% moisture content by maintain ing it at a temperature of 75 F. and relative humidity of 67% until the moisture content reached the 12% level.

Cigarettes were made from the papain-ficin-treated tobacco and from a control. These cigarettes were evaluated by a smoking panel of 25 members. Thesm'oke from the treated cigarettes was milder than that fromthe control cigarette. The results of these evaluations are given in Table IV below:

TABLE IV.-TEST PANEL EVALUATIONS OF LOW GRADE BRIGHT TOBACCO CONTAINING PAPAIN-FICIN Average rating* from 25 Panelists A scale of 5 to +5 was employed, 5 being the poorest rating, being the characteristics of the control, and being the best rating.

I claim:

1. A process for the treatment of tobacco which comprises adding to the tobacco, a non-living mixture consisting of from 93 to 97 parts byweight of water and from 3 to 7 parts by weight of a proteolytic enzyme selected from the group consisting of ficin, pepsin, trypsin, chymotrypsin, erepsin, fungal protease, protease and papain, said mixture being added in an amount to provide from about 1.4 to about 2.8 grams of said proteolytic enzyme per pound of tobacco and to provide a moisture content in the resulting tobacco composition of from about 15 to about 45 by Weight, subjecting the resulting tobacco composition without removing any portion thereof to a temperature of from about 60 F. to about 140 F. and a relative humidity of from about 45% to about 85% for a period of from about 1 to about 200 hours, bringing the moisture content of said tobacco composition to a value of from about to about by weight and thereafter incorporating the entire tobacco water-enzyme composition in a smoking product, whereby the resulting smoking product contains all of the products of the reactions of the tobacco-Waterenzyme composition and all of the unreacted components of the tobacco-water-enzyme composition.

2. A process for the treatment of tobacco which comprises adding to the tobacco a non-living material comprising an aqueous solution of a proteolytic enzyme selected from the group consisting of ficin, pepsin, trypsin, chymotrypsin, erepsin, fungal protease, protease and papain, said aqueous solution consisting of from 93 to 97 parts by weight of water and from 3 to 7 parts by weight of proteolytic enzyme, said aqueous solution being added in an amount to provide from about 1.4 to about 2.8 grams of said proteolytic enzyme per pound of tobacco and to provide a moisture content in the resulting tobacco composition of from about 15% to about 45% by weight, subjecting the resulting tobacco composition Without removing any portion thereof to a temperature of from about F. to about 140 F. and a relative humidity of from about 45% to about for a period of from about 1 to 200 hours bringing the moisture content of said tobacco composition to a value of from about 10% to about 15% by weight, by subjecting the composition to a temperature of from about 60 F. to about F., and thereafter incorporating the entire tobacco-water-enzyme composition in a smoking product, whereby the resulting smoking product contains all of the products of the reactions of the tobaccowater-enzyme composition and all of the unreacted components of the tobacco-water-enzyrne composition.

3. The process of claim 1 in which the enzyme is erepsin.

4. The process of claim 2 in which the enzyme is erepsin.

References Cited by the Examiner UNITED STATES PATENTS 2,475,568 7/1949 Moore 131-140 3,106,209 10/1963 Torigian "131-2 3,132,651 5/1964 Kiefer 131-141 FOREIGN PATENTS 252,121 10/1912 Germany.

OTHER REFERENCES I. B. Summer and G. F. Somers, Chemistry and Methods of Enzymes, pages 53 and 172, published 1953 by Academic Press Inc, New York, NY.

Shmuk, The Chemistry and Technology of Tobacco, volume III, pages 474 and 475, published for National Science Foundation, Washington, D.C., by Israel Program for Scientific Tnanslations in 1961.

Websters Third New International Dictionary, pages 770 and 1674, published 1961 by G. and E. Merriam Co., Springfield, Mass.

SAMUEL KOREN, Primary Examiner.

P. RAY CHAPPELL, MELVIN D. REIN, Examiner. 

1. A PROCESS FOR THE TREATMENT OF TOBACCO WHICH COMPRISES ADDING TO THE TOBACCO, A NON-LIVING MIXTURE CONSISTING OF FROM 93 TO 97 PARTS BY WEIGHT OF WATER AND FROM 3 TO 7 PARTS BY WEIGHT OF A PROTEOLYTIC ENZYNE SELECTED FROM THE GROUP CONSISTING OF FICIN, PEPSIN, TRYPSIN, CHYMOTRYPSIN, EREPSIN, FUNGAL PROTEASE, PROTEASE AND PAPAIN, SAID MIXTURE BEING ADDED IN AN AMOUNT TO PROVIDE FROM ABOUT 1.4 TO ABOUT 2.8 GRAMS OF SAID PROTEOLYTIC ENZYNE PER POUND OF TOBACCO AND TO PROVIDE A MOISTURE CONTENT IN THE RESULTING TOBACCO COMPOSITION OF FROM ABOUT 15% TO ABOUT 45% BY WEIGHT, SUBJECTING THE RESULTING TOBACCO COMPOSITION WITHOUT REMOVING ANY PORTION THEREOF TO A TEMPERATURE OF FROM ABOUT 60*F. TO ABOUT 140*F. AND A RELATIVE HUMIDITY OF FROM ABOUT 45% TO ABOUT 85% FOR A PERIOD OF FROM ABOUT 1 TO ABOUT 200 HOURS, BRINGING THE MOISTURE CONTENT OF SAID TOBACCO COMPOSITION TO A VALUE OF FROM ABOUT 10% TO ABOUT 15% BY WEIGHT AND THEREAFTER INCORPORATING THE ENTIRE TOBACCO-WATER-ENZYNE COMPOSITION IN A SMOKING PRODUCT, WHEREBY THE RESULTING SMOKING PORDUCT CONTAINS ALL OF THE PRODUCTS OF THE REACTIONS OF THE TOBACCO-WATERENZYNE COMPOSITION AND ALL OF THE UNREACTED COMPONENTS OF THE TOBACCO-WATER-ENZYNE COMPOSITION. 